/Engine/Source/Editor/UnrealEd/Classes/Editor/EditorEngine.h
Checks if a provided package is valid to be saved. For startup packages, it asks user for confirmation.
true if the provided package is valid to be saved
virtual bool IsPackageOKToSave ( [UPackage](API\Runtime\CoreUObject\UObject\UPackage) * InPackage, const [FString](API\Runtime\Core\Containers\FString) & InFilename, [FOutputDevice](API\Runtime\Core\Misc\FOutputDevice) * Error )